<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    let score = +prompt('请输入分数')
    if (score >= 0 && score < 60){
      alert('你不及格')
    } else if (score >= 60 && score < 80) {
      alert('你及格了')
    }else if (score >= 80 && score < 90) {
      alert('良好')
    }else if (score >= 90 && score <= 100) {
      alert('优秀')
    }else(
      alert('别乱写')
    )
    
  </script>
</body>
</html>